Blog post

Citrix, CloudStack, OpenStack, and the war for open-source clouds

By Lydia Leong | April 03, 2012 | 9 Comments


There are dozens upon dozens of cloud management platforms (CMPs), sometimes known as “cloud stacks” or “cloud operating systems”, out in the wild, both commercial and open source. Two have been in the news recently — Eucalyptus and CloudStack — with implications for the third, OpenStack.

Last week, Eucalyptus licensed Amazon’s API, and just yesterday, Wired extolled the promise of OpenStack.

Now, today, Citrix has dropped a bombshell into the open-source CMP world by announcing that it is contributing CloudStack (the Amazon-API-compatible CMP it acquired via its staggeringly expensive acquisition) to the Apache Software Foundation (ASF). This includes not just the core components, which are already open-source, but also all of the currently closed-source commercial components (except any third-party things that were licensed from other technology companies under non-Apache-compatible licenses).

I have historically considered CloudStack a commercial CMP that happens to have a token open-source core, simply because anyone considering a real deployment of CloudStack buys the commercial version to get all the features — you just don’t really see people adopting the non-commercial version, which I consider a litmus test of whether or not an open-core approach is really viable. This did change with Citrix, and the ASF move truly puts the whole thing out there as open source, so adopters have a genuine choice about whether or not they want to pay for commercial support, and it should spur more contributions from people and organizations that were opposed to the open-core model.

What makes this big news is the fact that OpenStack is a highly immature platform (it’s unstable and buggy and still far from feature-complete, and people who work with it politely characterize it as “challenging”), but CloudStack is, at this point in its evolution, a solid product — it’s production-stable and relatively turnkey, comparable to VMware’s vCloud Director (some providers who have lab-tested both even claim stability and ease of implementation are better than vCD). Taking a stable, featureful base, and adding onto it, is far easier for an open-source community to do than trying to build complex software from scratch.

Also, by simply giving CloudStack to the ASF, Citrix explicitly embraces a wholly-open, committer-driven governance model for an open-source CMP. Eucalyptus has already wrangled with its community over its open-core closed-extensions approach, and Rackspace is still strugging with governance issues even though it’s promised to put OpenStack into a foundation, because of the proposed commercial sponsorship of board seats. CloudStack is also changing from GPLv3 to the Apache license, which should remove some concerns about contributing. (OpenStack also uses the Apache license.)

Citrix, of course, stands to benefit indirectly — most people who choose to use CloudStack also choose to use Xen, and often purchase XenServer, plus Citrix will continue to provide commercial support for CloudStack. (It will just be a commercial distribution and support, though, without any additional closed-soure code.) And they rightfully see VMware as the enemy, so explicitly embracing the Amazon ecosystem makes a lot of sense. (Randy Bias has more thoughts on Citrix; read James Urquhart’s comment, too.)

Citrix has also explicitly emphasized Amazon compatibility with this announcement. OpenStack’s community has been waffling about whether or not they want to continue to support an Amazon-compatible API; at the moment, OpenStack has its own API but also secondarily supports Amazon compatibility. It’s an ecosystem question, as well as potentially an intellectual property issue if Amazon ever decides to get tetchy about its rights. (Presumably Citrix isn’t being this loud about compatibility without Amazon quietly telling them, “No, we’re not going to sue you.”)

I think this move is going to cause a lot of near-term soul-searching amongst the major commercial contributors to OpenStack. While clearly there’s value in working on multiple projects, each of the vendors still needs to place bets on where their engineering time and budgets are best spent. Momentum is with OpenStack, but it’s also got a long way to go.

HP has effectively recently doubled down on OpenStack; it’s not too late for them to change their mind, but for the moment, they’re committed in an OpenStack direction both for their public developer-centric cloud IaaS, and where they’re going with their hybrid cloud and management software strategy. No doubt they’ll end up supporting every major CMP that sees significant success, but HP is typically a slow mover, and it’s taken them this long to get aligned on a strategy; I’m not personally expecting them to shift anytime soon.

But the other vendors are largely free to choose — likely to support both for the time being, but there may be a strong argument for primarily backing an ASF project that’s already got a decent core codebase and is ready for mainstream production use, over spending the next year to two years (depending on who you talk to) trying to get OpenStack to the point where it’s a real commercial product (defined as meeting enterprise expectations for stable, relatively maintenance-free software).

The absence of major supporting vendor announcements along with the Citrix announcement is notable, though. Most of the big vendors have made loud commitments to OpenStack, commitments that I don’t expect anyone to back down on, in public, even if I expect that there could be quiet repositioning of resources in the background. I’ve certainly had plenty of confidential conversations with a broad array of technology vendors around their concerns for the future of OpenStack, and in particular, when it will reach commercial readiness; I expect that many of them would prefer to put their efforts behind something that’s commercially ready right now.

There will undoubtedly be some people who say that Citrix’s move basically indicates that CloudStack has failed to compete against OpenStack. I don’t think that’s true. I think that CloudStack is gaining better “real world” adoption than OpenStack, because it’s actually usable in its current form without special effort (i.e., compared to other commercial software) — but the Rackspace marketing machine has done an outstanding job with hyping OpenStack, and they’ve done a terrific job building a vendor community, whereas CloudStack’s primary committers have been, to date, almost solely

Both OpenStack and CloudStack can co-exist in the market, but if Citrix wants to speed up the creation of Amazon-compatible clouds that can be used in large-scale production by enterprises trying to do Amazon hybrid clouds (or more precisely, who want freedom to easily choose where to place their workloads), it needs to persuade other vendors to devote their efforts to enhancing CloudStack rather than pouring more time into OpenStack.

Note that with this announcement, Citrix also cancels Project Olympus, its planned OpenStack commercial distribution, although it intends to continue contributing to OpenStack. (Certainly they need to, if they’re going to support folks like Rackspace who are trying to do XenServer with OpenStack; the OpenStack deployments to date have been KVM for stability reasons.)

But it’s certainly going to be interesting out there. At this stage of the CMP evolution, I think that the war is much more for corporate commitment and backing with engineers paid to work on the projects, than it is for individual committers from the broader world — although certainly individual engineers (the open-source talent, so to speak) will choose to join the companies who work on their preferred projects.

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Comments are closed


  • Sebastien says:


    Can you just dive into your statement:

    “OpenStack is a highly immature platform”

    I would like to have more arguments.

    Thank you.

  • Saurabh Bhatia says:

    So ,who paid for the research to Gartner? Citrix ?

  • Lydia Leong says:

    @Sebastien: I would define three components of “immature”, but I use the word in the same sense it’s normally used in software. One is feature-completeness. One is stability. And one is the degree that the codebase’s core changes from release to release.

    OpenStack Swift, the storage component, that is basically Rackspace’s cloud storage service code open-sourced, is mature software. It’s production-ready, Rackspace had been using it in production for years, and it’s readily adopted. I don’t think anyone disputes that it’s good to go; cloud providers adopt it all the time, and it’s definitively won the scale-out object-based-store role in the open-source space.

    OpenStack Nova is another story entirely. It was essentially brand-new code that was created for the project. Brand-new code is essentially by definition immature; what is making people twitch at this point is that it doesn’t seem to be maturing quickly despite all the engineers working on OpenStack — and indeed, the sheer number of people working on it may in fact be contributing to the issue.

    OpenStack is nowhere near feature-complete, by comparison to other CMPs — whether Eucalyptus, CloudStack, or the huge number of commercial CMPs out there.

    OpenStack continues to have difficulty releasing stable code. I don’t think anyone seriously disputes this at this point in time — not the major vendors involved with OpenStack, not the little guys involved with OpenStack, and the management at those vendors as well as the engineers directly involved have become increasingly open about the challenges of working with the codebase.

    @Saurabh, please find something more meaningful to say than a tired pay-to-play accusation. Gartner analysts work on topics of interest to them, and service provider CMPs are of great interest to me. I’ve spent some time looking at CloudStack, but I’ve spent a much larger amount of time looking at OpenStack. I’ll be at the OpenStack conference.

  • Milind Patil says:

    Hello Lydia,

    First of all it is nicely written and quite fresh information, thank you for that.

    It appears to me from article that Citrix is not planning to have something like Olympus commercial distribution around CloudStack, I am right?


  • Lydia Leong says:

    Citrix will continue to have a commercial distribution of CloudStack but it will not have proprietary extensions.

  • koolhead17 says:

    I see Garter saying something similar about Linux 1990.

    Are you folks in habit of talking non-sense when it comes about open source and open innovation?

  • Lydia Leong says:

    Open source projects are not universally successful, just the same way that commercial closed-source projects are not universally successful. The quality of code, the complexity of the project, the governance structure, the license, the community, etc. all contribute enormously to the success of an open source project, both from an engineering perspective and from a customer adoption perspective. OpenStack is not analogous to Linux.

  • Igor says:

    Sebastien, have you ever tried to deploy OpenStack? Believe me, it _is_ immature. Yes, one can deploy it and probably even use it – in a some way. But it is far from production ready software solution for the moment. It may become industrial-grade in the future. But right now it is just a poorly documented set of python scripts, and nothing more.

  • Clement Chen says:

    Well written. Anyone who has actually tried to deploy OpenStack would NOT argue that it is immature. The only mature part of OpenStack is Swift and Cloudstack also uses it for its object storage.